With regard to an IC (Integrated Circuit) chip for communication, when a specified communication bus is shorted to a power supply or ground, it is possible that the temperature of the IC chip rises with the flow of an overcurrent and hence causes the thermal breakdown of a device. Typically, an overheat protecting function is provided for preventing the thermal breakdown of a device caused by an overcurrent, and the overheat protecting function is operated to stop an operation when the temperature reaches the specific temperature (i.e., the temperature is equal to or higher than 170° C. since an IC is operated at the temperature which is less than or equal to, for example, 150° C.).